/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2003-2008 University of Maryland
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.util;

import java.io.Serializable;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeSet;
import java.util.Map.Entry;

/**
 * @author pwilliam
 */
public class FractionalMultiset<K> {
	final Map<K, Double> map;
	
	public FractionalMultiset() {
		map = new HashMap<K, Double>();
	}

	public FractionalMultiset(Map<K,Double> map) {
		this.map = map;
	}

		
	public void clear() {
		map.clear();
	}

	public int numKeys() {
		return map.size();
	}

	public void add(K k, double val) {
		Double v = map.get(k);
		if (v == null)
			map.put(k, val);
		else
			map.put(k, v + val);
	}
	public double getValue(K k) {
		Double v = map.get(k);
		if (v == null)
			return 0;
		return v;
	}
	
	public void turnTotalIntoAverage(Multiset<K> counts) {
		for(Map.Entry<K,Double> e : map.entrySet()) {
			int count = counts.getCount(e.getKey());
			if (count == 0)
				e.setValue(Double.NaN);
			else
				e.setValue(e.getValue()/ count);
			
		}
	}
	public Iterable<Map.Entry<K, Double>> entrySet() {
		return map.entrySet();
	}

	
	public Iterable<Map.Entry<K, Double>> entriesInDecreasingOrder() {
		TreeSet<Map.Entry<K, Double>> result = new TreeSet<Map.Entry<K, Double>>(new DecreasingOrderEntryComparator<K>());
		result.addAll(map.entrySet());
		return result;
	}
	public Iterable<Map.Entry<K, Double>> entriesInIncreasingOrder() {
		TreeSet<Map.Entry<K, Double>> result = new TreeSet<Map.Entry<K, Double>>(new DecreasingOrderEntryComparator<K>());
		result.addAll(map.entrySet());
		return result;
	}

	private static <E> int compareValues(Entry<E, Double> o1, Entry<E, Double> o2) {
		double c1 = o1.getValue();
		double c2 = o2.getValue();
		if (c1 < c2)
			return 1;
		if (c1 > c2)
			return -1;
		return System.identityHashCode(o1.getKey()) - System.identityHashCode(o2.getKey());
	}

	static class DecreasingOrderEntryComparator<E> implements Comparator<Map.Entry<E, Double>>, Serializable {
		public int compare(Entry<E, Double> o1, Entry<E, Double> o2) {
			return compareValues(o1, o2);
		}
	}

	static class IncreasingOrderEntryComparator<E> implements Comparator<Map.Entry<E, Double>>, Serializable {
		public int compare(Entry<E, Double> o1, Entry<E, Double> o2) {
			return -compareValues(o1, o2);
		}
	}

}
